Air brake



June 15, 1937. c. A. CAMPBELL AIR BRAKE Filed Jan. 6, 1936 Patented June 15, 1937 UNITED STATES Y z,osa,ass

PATENT FFICE AIR BRAKE poration of New Jersey Application January 6, 1936, Serial No. 57,828

3 Claims.

This invention relates to brake cylinders for flu'id pressure railway bra.kes, end particularly to the means for supporting and guiding the tubular piston rod. customarily used in such brakes.

The present trend in the art is toward mounting the brake cylinders directly on the trucks, instead of mounting them on the car frame as was formerly the accepted practice. The tubular piston rod necessarily makes a. loose fit in its guide 0 which guide is carried by the front cylinder head (called in the art the non-pressure head) The present inventon provides means effective in release position to center the tubuiar piston rod. so that it cannot vibrate ansi cause wear. Such 15 wea.r has been found to be severe Where the cy1- inder is mounted on the truck because of the intense vibration encountered.

The invention takes advantage of the return spring to develop the centering force, and in its preferred form the eentering device is carried by the retaining ring for the lubricating a.nd dust excluding parts mounted in the piston rod guide.

The invention is illustrated in detail in the accompanying dra.wing wherein,-

Fig. 1 is an axial section through a brake cylinder showing one ernbodiment of ths invention.

Fig. 2 is an enlarged view of a. portion of Fig. 1 with the push rod. omitted.

Fig. 3 is a fragmentary sectio-nal view similar 30 to a portion of Fig. 2 the section being ta.ken on a.

different plane for the purpose of showing the manner in which the opposed inclined faces of the centering means engage.

Fig. 4 is a perspectve view of the retaining and 35 centering ring.

Fig. 5 is a. view in section showing the application of this invention to a. clevis type piston rod.

Referring to Figs. 1 to 4, the numeral 6 designates the body of a known type of brake cylinder. 1 is the front or non-pressure head end of the cylnder, 8 is the piston head, and 9 is the tubular piston rod which receives the usual push rod II.

The push rod I I is retained within the t1ibular 45 piston rod by 21. pin I2 which works loose1y in a. hole and is connected in the usual way to the brake rigging (not shown) by the pin 13 and clevis HL Return spring l5 urges the piston 8 toward release position.

Ai: its outer end the tubular piston rod passes loosely through, and is guided by, a bushng l6 fixed in the non-pressure head I. At the outer end of this bushing is a lubrcating ring I'I, and a plurality of wiper or dust-excluding rings 18.

55 They are confined Within a, recess l9 by a retaining plate 2| held by ca.p screws 22. Lubricant is supplied to this assembly through opening 23 closed by a threaded plug 24.

A colla.r 25 is secured to the end of piston rod 9 by pilot screws 26 provided with look washers 5 21.

The parts so far described will be recognized as a. known type of brake cyiinder and no novelty is here cla.imed therefor.

According to this invention the retaining ring 2| is provided With a plurality of arcuate bosses 28 formed on its outer face. The inner faces 29 of the bosses 28 fiare outward, see particularly Fig.

4. Cap screws 22 pass through openings 3| and secure the ring to the head I.

The inner face of the ring 2| is formed with an annular rib 32 which enters the recess |9 end centers the ring.

By this arrangement the rib 32 resists ali side thrust of the piston rod end consequently re- 1ieves the cap screws of shearing stress.

The collar has one edge beveled t.o mate with the flared faces 29 of bosses 28.

The arrangement shown in Fig. 5 is similar to that just described bui; applied to a. brake cylinder 25 whose piston is of the clevis type.

As shown the collar 25a is threaded upon the end of piston rod. 9a a.nd riveted thereto. Further it is provided With arms 33 ha.ving openings which reoeive the usual pin.

With either arrangement the operation is as foilows:

Upon release of pressure in the brake cylinder the piston head 8 is moved toward release positionby the return spring l5. As it aproaches, 35 but before it reaches its iimit of motion, collar 25 contacts bosses 28 and terminates inward movement of the piston.

The inclined or flared faces 29 coact with the colla.r 25 to center the piston rod, and the ex pansive efort of return spring l5 acting upon the piston effectively prevents any motion of the piston stem while the brakes are released.

While the invention has been described in some detail it Will be apparent to those familiar With the art that t is readily adaptable to' the various known forms of brake cylinders, and no necessary limitation to the disclosed form is implied.

' What is c1airned is,-

1. The combination of a. brake cylinder; a pis- 5 ton having a. piston rod; a. combined lubricating and dust excluding mea.ns carried by said brake cylinder; a retainer ring for said. lubricating and dust excluding means, said retainer ring having beveied. surfaces on one fece thereo-f; a collar carried by sad piston rod, said collar ha.ving a beveled fece aclapted to coact With the beveled faces of said retainer ring; and a spring rendering said coaction effective to center a.nd confine said piston rod against vibration as the rod approaches its limit of motion to-ward release position.

2. The combination of a brake cylinder having a piston rod guide; a piston working in said cylinder and having a, rod working freely in said guide; a spring urging said piston toward release position; beveled surfaces on said guide and on said rod, said beveled faces coacting to center 

